This disclosure relates to the field of well logging instruments conveyed by cable into and along the interior of a subsurface wellbore. More specifically, the disclosure relates to between-instrument couplers that include the capability of free and unlimited rotation of instruments attached to one side of the coupler while maintaining full electrical connection between such instrument and any components attached to the other side of the coupler.
Wireline electrical logging includes extending at least one electrically operated instrument into a wellbore at the end of an armored electrical cable. The armored electrical cable comprises at least one insulated electrical conductor and is covered on its exterior with one or more layers of helically wound armor wire. The armor wire layer(s) provide(s) tensile strength, bend resistance and abrasion resistance to the cable, among other functions. Because of the helical wind on many types of armored electrical cable used in well logging and other types of well intervention servicing, when the electrical cable undergoes changes in axial loading, the helical windings exert a torque as a result of unwinding caused by the axial loading. Such torque may hinder operation of some types of well logging instruments which may function better when the instrument is not subject to rotation in the wellbore resulting from the cable torque.